微粉末粒子充填ポリプロピレン射出成形物の分子鎖配向

II. 分子鎖配向過程の解析

抄録

The molecular orientation process during the injection molding of particulate filled polypropylenes was analyzed from the viewpoint of the growth of melt orientation (recoverable shear strain) at the gate and its relaxation in the mold cavity, based on rheological and thermal properties. The estimated variation of degree of orientation along the thicknesswise and the flow directions was well in accord with the experimental results of thickness of skin layer and degree of crystal orientation. Irrespective of differences in kind of filler, filler contents, and molding conditions, high correlation was obtained between the calculated average degree of molecular orientation and observed thickness of skin layer, or degree of crystal orientation. The observed increases of the thickness of skin layer and the degree of crystal orientation by the particulate filling were interpreted as due to i) long relaxation time of recoverable shear strain, ii) high thermal diffusivity, and iii) high crystallization temperature.